Light Seeds Research Articles

Unveiling the First Black Holes With JWST:Multi-wavelength Spectral Predictions

Abstract Growing supermassive black holes ( ) that power luminous quasars from light seeds—the remnants of the first stars—within a Gyr of the Big Bang poses a timing challenge. The formation of massive black hole seeds via direct collapse with initial masses alleviates this problem. Viable direct-collapse black hole formation sites, the satellite halos of star-forming galaxies, merge and acquire stars to produce a new, transient class of high-redshift objects, obese black hole galaxies (OBGs). The accretion luminosity outshines that of the stars in OBGs. We predict the multi-wavelength energy output of OBGs and growing Pop III remnants at z = 9 for standard and slim disk accretion, as well as high and low metallicities of the associated stellar population. We derive robust selection criteria for OBGs—a pre-selection to eliminate blue sources, followed by color–color cuts and the ratio of X-ray flux to rest-frame optical flux . Our cuts sift out OBGs from other bright, high- and low-redshift contaminants in the infrared. OBGs with predicted are unambiguously detectable by the Mid-Infrared Instrument (MIRI), on the upcoming James Webb Space Telescope (JWST). For parameters explored here, growing Pop III remnants with predicted will likely be undetectable by JWST. We demonstrate that JWST has the power to discriminate between initial seeding mechanisms.

Do Plants Have a Choice of Traits to Be Modulated? Evidence from an Invasive Plant <i>Mikania micrantha</i> Kunth in Different Urban Environments

The successful establishment of an invasive plant in a novel environment has been attributed to the phenotypic plasticity of plant traits, with most studies focussing on vegetative trait plasticity in either experimental and/or natural habitat conditions. This study explores the role of phenotypic plasticity, in both vegetative and reproductive traits, of an invasive plant Mikania micrantha growing as a ground cover in diverse urban areas in the city of Kolkata, India. Quadrat based plant and soil sampling was conducted in three habitat types, namely roadsides, natural areas and abandoned plots, from four regions within the city. The above ground biomass and fitness related vegetative and seed traits were estimated from the plant samples whereas soil macro-and micro-nutrients as well as soil health (in terms of organic carbon and microbial biomass carbon) were estimated from the soil samples. Habitat-specific selection of traits in M. micrantha was observed in this study. In roadside population which has more chances of long distance dispersal, the excessive production of reproductive biomass as a compensatory response to the low germination ability of the seeds was evident. In natural areas which are more prone to anthropogenic disturbance and where the plant has greater chances of local spread, modulation of both vegetative (higher SLA) and reproductive traits (lighter seeds with faster germination ability) helped the plant to maintain its population. In abandoned plots where there was more number of associated species, the longer span of germination and increased population height ensured the survivability of M. micrantha in the community. Thus, a continuous monitoring program to check for M. micrantha growth should be prioritized in urban areas due to its immense trait plasticity in different habitat conditions where uncontrolled growth can lead to its establishment and spread, thereby making its control more difficult.

Impact of Cardamom Cultivation on the Composition and Dynamics of Soil Seed Banks in a Conservation Forest in Sri Lanka: Implications for Conservation

Cultivation of cash crops, such as cardamom (Elettaria cardamomum) in the forest understorey is a common practice in many tropical forests. Over time, cultivation may change forest structure and species composition, leading to gradual degradation of biodiversity and ecosystem services. Effective conservation of these forests requires an enhanced understanding of the demographic processes such as soil seed bank that may greatly influence future forest composition. We examined how the soil seed bank structure and composition responds to cardamom cultivation in a high conservation value Sri Lankan montane rain forest. Soil samples from natural forest with abandoned cardamom plantations (CP) and adjacent natural forest (NF) patches without cardamom were collected in dry and wet seasons. Soil samples were spread out in trays in a shade house and germination was recorded weekly for 19 weeks. The density of seeds in the soil seed bank was much higher in CP than NF. While grasses and forbs contributed the highest number and percentage of seeds in soils of both forest types, their densities in the soil seed bank were 9 and 2 times greater in the CP than the NF, respectively. Seeds of the non-native herbs Ageratina riparia and E. cardamomum were 4 and 20 times greater in the soil of CP, respectively. Seeds of light demanding tree species such as Macaranga indica were restricted to soils of CPs. Overstorey tree community of each forest type was poorly represented in their respective soil seed banks. The high density of seeds of pioneer trees and non-native herbs in the soil of CPs, combined with higher light transmission to the ground floor may exacerbate competition for resources with the seedlings of late successional trees of high conservation value. To overcome this barrier and enhance conservation value of the forest, restoration strategies may need to focus on transplanting seedlings of these species into forest with abandoned cardamom plantations.

Importance of animal and plant traits for fruit removal and seedling recruitment in a tropical forest

The traits of animals and plants influence their interaction networks, but the significance of species' traits for the resulting ecosystem functions is poorly understood. A crucial ecosystem function in the tropics is seed dispersal by animals. While the importance of species' traits for structuring plant–frugivore networks is supported by a number of studies, no study has so far identified the functional traits determining the subsequent processes of fruit removal and seedling recruitment. Here, we conducted a comprehensive field study on fruit removal by frugivorous birds and seedling recruitment along an elevational gradient in the Colombian Andes. We measured morphological traits of birds (body mass, bill width, Kipp's index) and plants (plant height, crop mass, fruit width and seed mass) which we expected to be related to fruit removal and seedling recruitment. We tested 1) which bird and plant traits influence fruit removal, and 2) whether network metrics at plant species level, functional identities of frugivores (community‐based mean trait values) and/or plant traits were the main determinants of seedling recruitment. We found that large‐bodied bird species contributed more to fruit removal than small‐bodied bird species and that small‐sized fruits were more frequently removed than large‐sized fruits. Small plant species and plants with heavy seeds recruited more seedlings than did large plants and plants with light seeds. Network metrics and functional identities of seed dispersers were unrelated to seedling recruitment. Our findings have two important implications. First, large birds are functionally more important than small birds in tropical seed‐removal networks. Second, the detected tradeoff between fruit size and seed mass in subsequent recruitment processes suggests that the adaptability of forest plant communities to a loss of large frugivores is limited by life‐history constraints. Hence, the protection of large‐bodied frugivores is of primary importance for the maintenance of diverse tropical plant communities.

Влияние сортировки семян хвойных пород на посевные качества

The result of studies of the influence of seeds sorting of softwood species on their crop quality showed that each size fraction of heavy and average mass meet the requirements i.e. the energy of their germination and sprouting. They should also be used for sowing both in growing large-sized seedlings without prescrivere, and in the production of seeding with closed root sys-tem. It was also found that the light seeds of all size fractions have lower energy of sprouting and lower ground germination capacity that do not meet quality requirements and are not condi-tioned. These seeds are not good for sowing.

Light or heavy supermassive black hole seeds: the role of internal rotation in the fate of supermassive stars

Supermassive black holes are a key ingredient of galaxy evolution. However, their origin is still highly debated. In one of the leading formation scenarios, a black hole of ∼100 M⊙ results from the collapse of the inner core of a supermassive star (≳104–5 M⊙), created by the rapid accumulation (≳0.1 M⊙ yr−1) of pristine gas at the centre of newly formed galaxies at z ∼ 15. The subsequent evolution is still speculative: the remaining gas in the supermassive star can either directly plunge into the nascent black hole or part of it can form a central accretion disc, whose luminosity sustains a surrounding, massive, and nearly hydrostatic envelope (a system called a ‘quasi-star’). To address this point, we consider the effect of rotation on a quasi-star, as angular momentum is inevitably transported towards the galactic nucleus by the accumulating gas. Using a model for the internal redistribution of angular momentum that qualitatively matches results from simulations of rotating convective stellar envelopes, we show that quasi-stars with an envelope mass greater than a few 105 M| $_{\odot } \times (\rm black\ hole\ mass/100\,\mathrm{M}_{\odot })^{0.82}$ | have highly sub-Keplerian gas motion in their core, preventing gas circularization outside the black hole's horizon. Less massive quasi-stars could form but last for only ≲104 yr before the accretion luminosity unbinds the envelope, suppressing the black hole growth. We speculate that this might eventually lead to a dual black hole seed population: (i) massive (>104 M⊙) seeds formed in the most massive (>108 M⊙) and rare haloes; (ii) lighter (∼102 M⊙) seeds to be found in less massive and therefore more common haloes.

Mass-based germination dynamics of Rudbeckia mollis (Asteraceae) seeds following thermal and ageing stress

AbstractSeed mass is an important plant functional trait linked to germination. For instance, higher-mass seeds often display greater germination compared to lower-mass seeds when exposed to non-stressful conditions. Yet, knowledge pertaining to germination dynamics for different mass-based seed fractions following exposure to abiotic stress is lacking. Here, we assess the germination response of relatively fresh, mass-separated Rudbeckia mollis (Asteraceae) seeds to various simulated seasonal temperatures, supra-optimal temperatures and increasing ageing stress duration. Air density separation yielded three mass-based classes, called light (393 ± 35 μg), intermediate (423 ± 29 μg) and heavy (474 ± 38 μg). Water uptake kinetics indicated that imbibition (0–6 h) and germination lag (6–24 h) were independent of seed mass. Similarly, germination and viability loss of fresh seeds following exposure to seasonal and supra-optimal constant temperatures were independent of mass. However, seed mass influenced germination following increasing ageing stress, with light seeds germinating to a significantly greater extent than intermediate or heavy seeds. For example, final germination per cent in light-class seeds was about 1.7 times greater than intermediate or heavy seeds after 20 d of saturated salt accelerated ageing (SSAA). Seeds stored for 1 year in the laboratory displayed mass-dependent germination patterns similar to seeds following SSAA. Mass-independent germination responses may be a strategy to maintain an annual life history in otherwise difficult environments when R. mollis seeds are relatively fresh. However, differences in germination response between aged and unaged seeds suggest that mass-dependent viability loss may occur in R. mollis.

Impacts of short-term germination delay on fitness of the annual weed Agrostemma githago (L.)

AbstractTime of seedling emergence is an important step in the life cycle of annual plants because it may determine subsequent performance and success. Timing of emergence is especially critical to plant performance in habitats like arable fields which are subject to frequent disturbances. Within-season variation in timing of germination in the range of only a few days is typical for many arable weeds. However, since it is unclear whether such small deviations in germination date translate into fitness differences in the course of the life cycle, the aim of this paper was to quantify the effects of short germination delays on plant performance. We conducted two generalized randomized block experiments in an unheated greenhouse to study the impact of delayed germination (1, 2, 3 and 7 d) with and without competition, respectively, on the fitness of the arable weed species Agrostemma githago (L.). We expected that delayed germination significantly reduces fitness in terms of several life-history traits, and that the decrease of fitness is higher in the presence of competition. Under realistic conditions with competition through barley, Agrostemma plants with delayed germination of 7 d produced 54% fewer shoots, 57% less biomass, 52% fewer flowers, 36% lighter seeds and were 23% shorter as compared to control plants without delayed germination. Without additional stress through competition with barley this pattern was less pronounced. Thus, in the situation of interspecific competition, early emerging seedlings have biologically significant fitness advantages over later emerging seedlings of the same species.

From the first stars to the first black holes

The growth of the first super massive black holes (SMBHs) at z > 6 is still a major challenge for theoretical models. If it starts from black hole (BH) remnants of Population III stars (light seeds with mass ~ 100 Msun) it requires super-Eddington accretion. An alternative route is to start from heavy seeds formed by the direct collapse of gas onto a ~ 10^5 Msun BH. Here we investigate the relative role of light and heavy seeds as BH progenitors of the first SMBHs. We use the cosmological, data constrained semi-analytic model GAMETE/QSOdust to simulate several independent merger histories of z > 6 quasars. Using physically motivated prescriptions to form light and heavy seeds in the progenitor galaxies, we find that the formation of a few heavy seeds (between 3 and 30 in our reference model) enables the Eddington-limited growth of SMBHs at z > 6. This conclusion depends sensitively on the interplay between chemical, radiative and mechanical feedback effects, which easily erase the conditions that allow the suppression of gas cooling in the low metallicity gas (Z < Zcr and JLW > Jcr). We find that heavy seeds can not form if dust cooling triggers gas fragmentation above a critical dust-to-gas mass ratio (D > Dcr). In addition, the relative importance of light and heavy seeds depends on the adopted mass range for light seeds, as this dramatically affects the history of cold gas along the merger tree, by both SN and AGN-driven winds.

Seeds of Light, Flowers of Power, Fruits of Change

Ecowomanism focuses on the relationships between humans and nature through a spiritualized lens. Three core principles of ecowomanism are Livingkind (all living things are of a type), Aliveness (life pervades all creation, visible and invisible), and Luminosity (all living things are filled with light and spirit). Ecowomanism makes a unique, spiritually infused, ecological activist praxis possible. Three notable exemplars of this praxis are Sister Chan Khong (who established Sweet Potato Farm in France as part of her mindfulness-based peace activism), Kiran Bedi (who elevated the dignity of prisoners through her beautification of Tihar Jail/Ashram in India), and Wangari Maathai (who conscientized members of the Kenyan military by helping them to see the value of protecting the natural environment and planting trees as part of the Green Belt Movement).

Determination of fatty acids content, global antioxidant activity and energy value of weed seeds from agricultural fields in France

SummaryThe ecological consequences of seed size variation have been studied extensively in plants. Curiously, little attention has been paid to the qualitative and quantitative variation of the seed‐stored molecules and on their ecological significance. Here, we analysed the oil content and oil composition of ca. 200 weed seed species from agricultural fields in France based on single seed accessions, concentrating on interspecies differences and ignoring within‐species variation. The relationships between seed weight, oil %, fatty acids (FAs) and the energetic value of the seed and its antioxidant properties were also investigated. The antioxidant activity could contribute to protect the oily seed reserves from alteration over time. Among the species analysed, we found a considerable quantitative (oil%) and qualitative variation of FAs stored in the seeds. Such variation was largely related to the plant family of the different species, but intrafamily variation was also found. Heavier seeds contained less oil on a per gram basis than lighter seeds, suggesting a trade‐off between seed weight and oil ratio in the seed and that oil storage strategy depends on seed size. Moreover, oily seeds contained more polyunsaturated FAs. However, contrary to our hypothesis, we did not found a higher antioxidant capability in oily seed extracts than in non‐oily seeds, nor to the quantitative or to the qualitative variation of FAs in the seeds. Considering the role of these important trait variations on weed ecological strategies, such as germination period, seed predation rate and competition–colonisation trade‐off, could improve the sustainable management of weed communities.

Endozoochorous seed dispersal by Japanese macaques (Macaca fuscata): Effects of temporal variation in ranging and seed characteristics on seed shadows.

Variation in seed shadows generated by frugivores is caused by daily, seasonal, and inter-annual variation in ranging, as well as inter-specific variability in gut passage times according to seed characteristics. We studied the extent to which seed weight, specific gravity, and daily (morning, afternoon, and evening) and inter-annual (2004 vs. 2005) variation in ranging affected seed shadows generated by wild Japanese macaques (Macaca fuscata) in northern Japan. The macaques ingested fleshy fruits of 11 species during the two year study period; Viburnum dilatatum (Caprifoliaceae: heavier seeds with higher specific gravity) and Rosa multiflora (Rosaceae: lighter seeds with lower specific gravity) were eaten frequently in both years. The travel distances of macaques after feeding on V. dilatatum and R. multiflora fruits were estimated by combining feeding locations and ranging patterns measured in the field with gut passage times of model seeds in captive animals. Median travel distances after fruit feeding were 431 (quantile range: 277-654) and 478 m (265-646), respectively, with a maximum of 1,261 m. Neither year nor time of day affected travel distances. The gut passage time of model V. dilatatum seeds was longer than that of model R. multiflora seed, but this did not affect dispersal distances. Seed shadows for both species over 2 years showed unimodal distribution (peak: 101-500 m) and more than 90%, 20%, and 3% of ingested seeds were estimated to be dispersed >100, >500, and >1000 m, respectively, the longest known distances among macaque species. R. multiflora seeds tended to be dispersed further in 2004 than 2005, but V. dilatatum seeds were not, implying that inter-annual variations in ranging pattern due to the distribution and abundance of nut fruiting could affect dispersal distance.

The zinc finger transcription factor SlZFP2 negatively regulates abscisic acid biosynthesis and fruit ripening in tomato.

Abscisic acid (ABA) regulates plant development and adaptation to environmental conditions. Although the ABA biosynthesis pathway in plants has been thoroughly elucidated, how ABA biosynthetic genes are regulated at the molecular level during plant development is less well understood. Here, we show that the tomato (Solanum lycopersicum) zinc finger transcription factor SlZFP2 is involved in the regulation of ABA biosynthesis during fruit development. Overexpression of SlZFP2 resulted in multiple phenotypic changes, including more branches, early flowering, delayed fruit ripening, lighter seeds, and faster seed germination, whereas down-regulation of its expression caused problematic fruit set, accelerated ripening, and inhibited seed germination. SlZFP2 represses ABA biosynthesis during fruit development through direct suppression of the ABA biosynthetic genes NOTABILIS, SITIENS, and FLACCA and the aldehyde oxidase SlAO1. We also show that SlZFP2 regulates fruit ripening through transcriptional suppression of the ripening regulator COLORLESS NON-RIPENING. Using bacterial one-hybrid screening and a selected amplification and binding assay, we identified the (A/T)(G/C)TT motif as the core binding sequence of SlZFP2. Furthermore, by RNA sequencing profiling, we found that 193 genes containing the SlZFP2-binding motifs in their promoters were differentially expressed in 2 d post anthesis fruits between the SlZFP2 RNA interference line and its nontransgenic sibling. We propose that SlZFP2 functions as a repressor to fine-tune ABA biosynthesis during fruit development and provides a potentially valuable tool for dissecting the role of ABA in fruit ripening.

Hot Water Enhanced Germination of Leucaena Leucocephala Seeds in Light and Dark Conditions

Leucaena leucocephala has a great potential in crop and livestock production. However, the plant is difficult to propagate from both seeds and stem cuttings Scarification treatment has the prospective of enhancing seed germination. Chemicals and water have been used for seed scarification. This study evaluated the effectiveness of hot and boiling water in enhancing the germination of Leucaena leucocephala seed. Information on the condition (light or dark) at which Leucaeana seeds germinate better is also provided. The seeds were immersed in hot water and boiling water for 1, 2, 3, and 4 minutes respectively. At twenty-one days after the set-up of the experiment, untreated L. leucocephala seeds had 0 % and 13.3 % germinations under light and dark conditions respectively.; seeds immersed in boiling water for 1- 4 minutes did not germinate irrespective of the condition of germination while all the seeds immersed in hot water for one to three minutes had total (100%) germination; delaying the period of immersing the seeds in hot water to four minutes resulted in significantly less percentage germination than the aforementioned ones immersed in hot water for one to three minutes but had significantly greater germination than the untreated seeds. Dark and light conditions resulted in similar percentage seed germination outcome. Immersing Leucaena leucocephala seeds for one minute is recommended. Planting seeds in dark condition is recommended since continuous light provided no additional germination outcome, in spite of the additional cost of providing continuous light in the growth of seeds under light condition.

Estresse hídrico e massa de sementes na germinação e crescimento de plântulas de Amburana cearensis (Allemão) A.C. Smith

Amburana cearensis, conhecida como cumaru, é uma espécie presente em todo bioma caatinga, sendo recomendada para recuperação de áreas degradadas e usos fitoterápicos. O objetivo do presente trabalho foi determinar os níveis de tolerância ao estresse hídrico na germinação e no crescimento de plântulas de cumaru em função da massa das sementes. Inicialmente as sementes foram pesadas e separadas em três classes (leves, médias e pesadas), sendo estas submetidas ao estresse hídrico, utilizando soluções de Polietilenoglicol 6000, em diferentes potenciais (0,0; -0,2; -0,4; - 0,6; -0,8 e -1,0 MPa) e colocadas para germinar na temperatura de 30 °C em câmaras de germinação. O delineamento experimental foi inteiramente casualizado em esquema fatorial 3 x 6 (classes de massa x potencial hídrico). Para a avaliação da germinação, foram determinados a primeira contagem, porcentagem final e índice de velocidade de germinação, enquanto para a avaliação do crescimento das plântulas determinou-se o comprimento e massa seca do epicótilo e do eixo raiz + hipocótilo e a razão parte aérea/raiz. Os dados foram submetidos ao teste de normalidade e quando se apresentaram normais, realizou-se análise de variância, comparação de médias e regressão. O decréscimo do potencial hídrico prejudica a germinação e o crescimento de plântulas oriundas de sementes médias e pesadas em relação às leves, sendo a partir do potencial -0,6 MPa uma condição estritamente limitante na formação de plântulas normais de A. cearensis.

Ukuran Benih Dan Skarifikasi Dengan Air Panas Terhadap Perkecambahan Benih Pohon Kuku (Pericopsis Mooniana)

Nedun tree (Pericopsis mooniana) is one of commercial trees. The propagation of nedun tree generatively has an obstacle due to it’s dormant character and the variety of seeds weight and the both factors are suspected influence the germanitaion. This research aimed to determine effect of seed weight for nedun seed germination and the best of seeds weight for nedun seed germination; the effect of soaking in hot water at beginning temperature 80˚C by different soaking period on germination, and the best effect of soaking in hot water at beginning temperature of 80˚C by different soaking period on germination. This research was compiled in a randomized complete block design, with 5 treatments and 3 groups. Seeds were catagorized in to three group of weight which were heavy, medium, and light. The treatments consisted of without scarification (as a control), soaking in hot water at beginning temperature of 80ºC during 12 hours, 24 hours, 36 hours, and 48 hours. Every experiment unit consisted of 100 seed. The observed variables were consisted of germination percentage, mean daily germination, germination value, and the ability to germinate. Data analysis methods were used variance homogenity, variance analysis and least of difference test at 5% significant level. Based on the analysis of variance showed that seeds weight significantly affected the mean daily germination, but had no effect on germination percentage, germination value, and the ability to germinate. Seeds weight had a mean daily germination 15.088 days to germinate. The medium seeds were germinated faster than heavy seeds and light seeds. Seed scarification gave effect on germination percentage and germination value significantly, but not significant on mean daily germination and ability to germinate. Seeds scarification with hot water at beginning temperature 80°C for 48 hours had germination percentage 28,000%, germination percentage was better than the scarification for 36 hours, 24 hours, 12 hours, and control.

Taxonomic significance of capsule and seed characters of Indian species of Murdannia Royle (Commelinaceae)

Capsule and seed morphology of 26 species of Murdannia in India are studied using light microscopy and seeds of 23 species by scanning electron microscopy. The capsules show differences in size, shape and in the number and arrangement of seeds in the locules. The seeds also display considerable variation in size, shape, ornamentation, shape of hilum and position of embryotega. The present study provides useful characters for the delimitation of Indian species of Murdannia.

Reproductive traits and their correlation among woody plants in a broadleaf-Korean pine (&amp;lt;italic&amp;gt;Pinus koraiensis&amp;lt;/italic&amp;gt;) mixed forest in Northeast China

We examined the sexual reproduction of woody plants in a 25-hm2 plot of broadleaf–Korean pine(Pinus koraiensis) mixed forest in the Changbai Mountains, Northeast China. Reproductive traits differed among species, and sexual systems were associated with pollination syndromes, fruit types, seed mass and life forms. Among the species present in the plot, 49% were hermaphroditic, 27.5% were monoecious and 23.5% were dioecious. The percentage of monoecious species in the forest studied was higher than that of tropical forests. The flowering phenology among species was almost synchronous, whereas fruiting phenology varied greatly among species. Seed weight differed dramatically among different sexual systems and between life forms. Monoecious species produced the heaviest seeds, whereas hermaphroditic species produced the lightest seeds. Seeds of shrubs were heavier those of trees. In general, complex correlations were observed among reproductive traits and ecological characteristics in the broadleaf–Korean pine mixed forest, which was characterized by a generally entomophilous pollination syndrome among the common species and a high proportion of monoecious species.

Clonal ability, height and growth form explain species’ response to habitat deterioration in Fennoscandian wooded meadows

Fennoscandian calcareous wooded meadows have high conservation value due to very high diversity which has been maintained by consistent mowing, but undergo species loss when this management is abandoned. We compared species richness and composition of regularly mown and abandoned wooded meadows in Estonia and established species groups with respect to their response to abandonment. These meadows were very species rich with a maximum of 43 species per 0.25 m2. Species whose populations are maintained by mowing constituted >60 % of the floristic diversity of the mown wooded meadows. Abandonment suppressed species with a preference for dry infertile open habitats. Response to abandonment was related to clonality, height and growth form. The greatest negative response was associated with low graminoids, short-lived and non-clonal species, rosette and semi-rosette growth form. Weak competitors with low height and light seeds exhibited a slow decline; perennial life span and clonality enable a delay in local extinction of these species. Response groups had similar persistence at a national level, revealing that earlier assessment of species dynamics at larger spatial scales could underestimate the number of threatened species. Application of restoration measures could avoid local extinctions of many mowing-supported species, whereas some of the mowing-dependent species likely need reintroduction.

SUPER-CRITICAL GROWTH OF MASSIVE BLACK HOLES FROM STELLAR-MASS SEEDS

We consider super-critical accretion with angular momentum onto stellar-mass black holes as a possible mechanism for growing billion-solar-mass holes from light seeds at early times. We use the radiatively-inefficient "slim disk" solution -- advective, optically thick flows that generalize the standard geometrically thin disk model -- to show how mildly super-Eddington intermittent accretion may significantly ease the problem of assembling the first massive black holes when the Universe was less than 0.8 Gyr old. Because of the low radiative efficiencies of slim disks around non-rotating as well as rapidly rotating holes, the mass e-folding timescale in this regime is nearly independent of the spin parameter. The conditions that may lead to super-critical growth in the early Universe are briefly discussed.